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Zooplankton of Oman Coastal Waters

Sergey A. Piontkovski1*, Asila Al-Maawali2, Ward Al-Muna Al-Manthri1, Khalid Al-Hashmi1, and Elena A. Popova3
1College of Agricultural and Marine Sciences, Sultan Qaboos University
P.O. Box 34, Al-Khod 123, Sultanate of Oman
2 Marine Science Fisheries Centre, Ministry of Agriculture and Fisheries Wealth
P.O. Box 227, Sultanate of Oman
3Institute of Biology of the Southern Seas, 2 Nakhmov av.-Crimea
99011,Sevastopol, Ukraine

Monthly sampling during daytime was carried out in 2007-2011 at Bandar Al-Khyran (23.51oN, 58.72oE) which is the largest semi-enclosed bay on the southern end of the Sea of Oman with about 4 km2 in surface area and an average depth of 10 m. Zooplankton were represented by Copepoda (79%), Cladocera (9%), Oikopleuriddae (7%), Chaetognatha (3%), and Decapoda (~2%) comprising the major part of the total zooplankton abundance. Among copepods, 27 species constituted ~75% of total copepod abundance. Changes of copepod abundance have not had a pronounced seasonal pattern. Instead, a multiple peak structure in monthly fluctuations was observed, on the level of genera as well as the abundance of species. Amplitudes and timing of the copepod peak abundance were markedly different during the studied years.

Keywords: Copepods, zooplankton, the Arabian Sea.

Atmospheric cyclones and seasonal cycles of biological productivity of the ocean

Sultan Qaboos University, PO Box 34, Al-Khod 123, Sultanate of Oman

Remotely sensed wind speed, translation speed, atmospheric pressure, atmospheric precipitation rate and chlorophyll-a concentration were used to verify the hypothesis that the response of the phytoplankton community to propagating atmospheric cyclones should be associated with the phase of the seasonal cycle of this community and the translation speed of a cyclone. For the 12 cyclones investigated from the Indian Ocean, Pacific Ocean and the Mediterranean Sea the maximal sustained wind speed varied twofold, whereas the translation speed of cyclones and the chlorophyll ratio (characterizing chlorophyll concentration before and after cyclone passage) varied by 10-fold. It was shown that cyclones affecting the phytoplankton community approaching its seasonal maximum either could not stimulate or stimulated a weak response of further increase of chlorophyll-a concentration (due to explicitly available nutrients). Controversially, cyclones affecting the community approaching its seasonal minimum could induce gradual increase of chlorophyll-a concentration. An exponential type of relationship between chlorophyll ratio and translation speed of cyclones was evaluated. In the range of translation speeds from 1 to 10 ms−1, the increase of chlorophyll- a concentration due to cyclone passage was most pronounced with regard to slow moving cyclones.

Keywords: Atmospheric cyclones; Chlorophyll-a; Arabian Sea

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